The activated sludge process was discovered in 1913. Experiments on treating sewage in a draw-and-fill reactor (the precursor to today's sequencing batch reactor) produced a highly treated effluent. Believing that the sludge had been activated (in a similar manner to activated carbon) the process was named activated sludge. Not until much later was it realized that what had actually occurred was a means to concentrate biological organisms, decoupling the liquid retention time (ideally, low, for a compact treatment system) from the solids retention time (ideally, fairly high, for an effluent low in BOD5 and ammonia.) In a sewage (or industrial wastewater) treatment plant, the activated sludge process can be used for one or several of the following purposes including oxidizing carbonaceous matter: biological matter, oxidizing nitrogeneous matter such as ammonium and nitrogen in biological materials, removing phosphate, driving off entrained gases carbon dioxide, ammonia, nitrogen, etc, generating a biological floc, and generating a liquor low in dissolved or suspended material. Regardless of the reason for making the activated sludge, once the intended use is achieved, there remains a need to deactivate and dispose of the activated sludge in an efficient and cost effective manner. Accordingly, research continues in an effort to develop methods for accomplishing the deactivation and disposal of the sludge.